Electroluminescent display device

ABSTRACT

An electroluminescent display device is disclosed. The electroluminescent display device includes a substrate having thereon a first sub pixel and a second sub pixel, a first electrode in each of the first sub pixel and the second sub pixel on the substrate, an organic layer with P-type polarity or N-type polarity on the first electrode, and a second electrode on the organic layer. The organic layer provided in the first sub pixel and the organic layer provided in the second sub pixel are spaced apart from each other with a doping layer provided in the boundary area between the first sub pixel and the second sub pixel. The doping layer is doped with dopant whose polarity is opposite to that of the organic layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the Korean Patent Application No.10-2019-0133406 filed on Oct. 25, 2019, which are hereby incorporated byreference as if fully set forth herein.

BACKGROUND Technical Field

The present disclosure relates to an electroluminescent display device.

Description of the Related Art

An electroluminescent display device is provided in such a way that anemission layer is provided between an anode electrode and a cathodeelectrode, and the emission layer emits light by an electric fieldgenerated between the above two electrodes, to thereby display an image.

The emission layer may be formed of an organic material which emitslight when an exciton is produced by a bond of electron and hole, andthe exciton falls to a ground state from an excited state, or may beformed of an inorganic material such as quantum dot.

The emission layer may be configured to emit different colored light byeach sub pixel, for example, red colored light, green colored light andblue colored light, or may be configured to emit the same colored lightby each sub pixel, for example, white colored light.

BRIEF SUMMARY

The inventors of the present disclosure have realized that among manyother problems in the related art, a leakage current may be generateddue to a transfer of electric charges between the neighboring subpixels, whereby it may cause a deterioration of picture quality. Havingappreciating the problems in the related art, one or more embodiments ofthe present disclosure provides an electroluminescent display devicecapable of reducing a deterioration of picture quality caused by aleakage current between neighboring sub pixels.

In accordance with an aspect of the present disclosure, the above andother technical benefits can be accomplished by the provision of anelectroluminescent display device. The electroluminescent display deviceincludes a substrate having a first sub pixel and a second sub pixel, afirst electrode in each of the first sub pixel and the second sub pixelon the substrate, a first emission layer on the first electrode, acharge generation layer on the first emission layer, a second emissionlayer on the charge generation layer, and a second electrode on thesecond emission layer, wherein the charge generation layer includes anN-type charge generation layer on the first emission layer, and a P-typecharge generation layer on the N-type charge generation layer, and theN-type charge generation layer provided in the first sub pixel and theN-type charge generation layer provided in the second sub pixel arespaced apart from each other with a P-type doping layer provided in theboundary area between the first sub pixel and the second sub pixel.

In accordance with another aspect of the present disclosure, there isprovided an electroluminescent display device including a substratehaving a first sub pixel and a second sub pixel, a first electrode ineach of the first sub pixel and the second sub pixel on the substrate,an emission layer having a hole transport layer on the first electrode,and a second electrode on the emission layer, wherein the hole transportlayer provided in the first sub pixel and the hole transport layerprovided in the second sub pixel are spaced apart from each other withan N-type doping layer provided in the boundary area between the firstsub pixel and the second sub pixel.

In accordance with a further aspect of the present disclosure, there isprovided an electroluminescent display device including a substratehaving a first sub pixel and a second sub pixel, a first electrode ineach of the first sub pixel and the second sub pixel on the substrate,an organic layer with P-type polarity or N-type polarity on the firstelectrode, and a second electrode on the organic layer, wherein theorganic layer provided in the first sub pixel and the organic layerprovided in the second sub pixel are spaced apart from each other with adoping layer provided in the boundary area between the first sub pixeland the second sub pixel, and the doping layer is doped with dopantwhose polarity is opposite to that of the organic layer.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings. In the drawings:

FIG. 1 is a schematic cross sectional view illustrating anelectroluminescent display device according to one embodiment of thepresent disclosure;

FIGS. 2A to 2C illustrate a LUMO level and a HOMO level in a chargegeneration layer according to one embodiment of the present disclosure;

FIG. 3 is a graph of a current density change in accordance with adriving voltage according to one embodiment of the present disclosure;

FIG. 4 is a schematic cross sectional view illustrating anelectroluminescent display device according to another embodiment of thepresent disclosure;

FIG. 5 is a schematic cross sectional view illustrating anelectroluminescent display device according to another embodiment of thepresent disclosure;

FIG. 6 is a schematic cross sectional view illustrating anelectroluminescent display device according to another embodiment of thepresent disclosure;

FIG. 7 is a schematic plan view illustrating the electroluminescentdisplay device according to one embodiment of the present disclosure;

FIG. 8 is a schematic plan view illustrating the electroluminescentdisplay device according to another embodiment of the presentdisclosure; and

FIGS. 9A to 9C illustrate an electroluminescent display device accordingto another embodiment of the present disclosure, which relate to a headmounted display (HMD) device.

DETAILED DESCRIPTION

Advantages and features of the present disclosure, and implementationmethods thereof will be clarified through the following embodiments,described with reference to the accompanying drawings. The presentdisclosure may, however, be embodied in different forms and should notbe construed as being limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete, and will fully convey the scope of the presentdisclosure to those skilled in the art.

The shapes, sizes, ratios, angles, and numbers disclosed in the drawingsfor describing embodiments of the present disclosure are merelyexamples, and thus the present disclosure is not limited to theillustrated details. Like reference numerals refer to like elementsthroughout. In the following description, when the detailed descriptionof the relevant known function or configuration is determined tounnecessarily obscure the important point of the present disclosure, thedetailed description will be omitted.

In the case in which “comprise,” “have,” and “include” described in thepresent specification are used, another part may also be present unless“only” is used. The terms in a singular form may include plural formsunless noted to the contrary.

In construing an element, the element is construed as including an errorregion although there is no explicit description thereof.

In describing a positional relationship, for example, when thepositional order is described as “on,” “above,” “below,” “beneath”, and“next,” the case of no contact therebetween may be included, unless“just” or “direct” is used. If it is mentioned that a first element ispositioned “on” a second element, it does not mean that the firstelement is essentially positioned above the second element in thefigure. The upper part and the lower part of an object concerned may bechanged depending on the orientation of the object. Consequently, thecase in which a first element is positioned “on” a second elementincludes the case in which the first element is positioned “below” thesecond element as well as the case in which the first element ispositioned “above” the second element in the figure or in an actualconfiguration.

In describing a temporal relationship, for example, when the temporalorder is described as “after,” “subsequent,” “next,” and “before,” acase which is not continuous may be included, unless “just” or “direct”is used.

It will be understood that, although the terms “first,” “second,” etc.,may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present disclosure.

It should be understood that the term “at least one” includes allcombinations related with any one item. For example, “at least one amonga first element, a second element and a third element” may include allcombinations of two or more elements selected from the first, second andthird elements as well as each element of the first, second and thirdelements.

Features of various embodiments of the present disclosure may bepartially or overall coupled to or combined with each other, and may bevariously inter-operated with each other and driven technically as thoseskilled in the art can sufficiently understand. The embodiments of thepresent disclosure may be carried out independently from each other, ormay be carried out together in a co-dependent relationship.

In the drawings, the same or similar elements are denoted by the samereference numerals even though they are depicted in different drawings.

In the embodiments of the present disclosure, a source electrode and adrain electrode are distinguished from each other, for convenience ofexplanation. However, the source electrode and the drain electrode areused interchangeably. Thus, the source electrode may be the drainelectrode, and the drain electrode may be the source electrode. Also,the source electrode in any one embodiment of the present disclosure maybe the drain electrode in another embodiment of the present disclosure,and the drain electrode in any one embodiment of the present disclosuremay be the source electrode in another embodiment of the presentdisclosure.

In one or more embodiments of the present disclosure, for convenience ofexplanation, a source region is distinguished from a source electrode,and a drain region is distinguished from a drain electrode. However,embodiments of the present disclosure are not limited to this structure.For example, a source region may be a source electrode, and a drainregion may be a drain electrode. Also, a source region may be a drainelectrode, and a drain region may be a source electrode.

Hereinafter, an electroluminescent display device according to thepresent disclosure will be described with reference to the accompanyingdrawings.

FIG. 1 is a schematic cross sectional view illustrating anelectroluminescent display device according to one embodiment of thepresent disclosure.

As shown in FIG. 1, the electroluminescent display device according toone embodiment of the present disclosure includes a substrate 100, acircuit device layer 200, a first electrode 300, a bank 400, a firstemission layer 500, a charge generation layer 600, a second emissionlayer 700, and a second electrode 800.

The substrate 100 may be formed of glass or plastic, but not limited tothese materials. The substrate 100 may be formed of a semiconductormaterial such as silicon wafer. The substrate 100 may be formed of atransparent material or an opaque material. On the substrate 100, thereare a first sub pixel (SP1), a second sub pixel (SP2), and a third subpixel (SP3). For example, the first sub pixel (SP1) may emit red (R)colored light, the second sub pixel (SP2) may emit green (G) coloredlight, and the third sub pixel (SP3) may emit blue (B) colored light,but not limited to this structure.

The electroluminescent display device according to one embodiment of thepresent disclosure may be formed in a top emission type where emittedlight advances upwardly. If the electroluminescent display device isformed in the top emission type, the substrate 100 may be formed of anopaque material as well as a transparent material.

The circuit device layer 200 is provided on the substrate 100.

In the circuit device layer 200, a circuit device comprising varioussignal lines, thin film transistors, and a capacitor is provided by eachsub pixel (SP1, SP2, SP3). The signal lines may include a gate line, adata line, a power line, and a reference line, and the thin filmtransistors may include a switching thin film transistor, a driving thinfilm transistor, and a sensing thin film transistor.

The switching thin film transistor is switched by a gate signal suppliedto the gate line, and the switching thin film transistor supplies a datavoltage, which is supplied from the data line, to the driving thin filmtransistor.

The driving thin film transistor is switched by the data voltagesupplied from the switching thin film transistor, and the driving thinfilm transistor generates a data current based on a power sourcesupplied from the power line, and supplies the data current to the firstelectrode 300.

The sensing thin film transistor senses a deviation of a thresholdvoltage in the driving thin film transistor, which causes adeterioration of picture quality. The sensing thin film transistorsupplies a current of the driving thin film transistor to the referenceline in response to a sensing control signal supplied from the gate lineor an additional sensing line.

The capacitor maintains the data voltage supplied to the driving thinfilm transistor for one frame period, and the capacitor is connectedwith each of gate and source terminals of the driving thin filmtransistor.

The first electrode 300 is provided on the circuit device layer 200, andis patterned by each sub pixel (SP1, SP2, SP3). That is, one of thefirst electrode 300 is formed in the first sub pixel (SP1), anotherfirst electrode 300 is formed in the second sub pixel (SP2), and anotherfirst electrode 300 is formed in the third sub pixel (SP3). The firstelectrode 300 may function as an anode of the electroluminescent displaydevice.

The first electrode 300 is connected with the driving thin filmtransistor provided in the circuit device layer 200. In detail, thefirst electrode 300 may be connected with the source terminal or a drainterminal of the driving thin film transistor. To this end, a contacthole for exposing the source terminal or the drain terminal of thedriving thin film transistor is provided in the circuit device layer200, and the first electrode 300 is connected with the source terminalor the drain terminal of the driving thin film transistor via thecontact hole.

If the electroluminescent display device according to one embodiment ofthe present disclosure is formed in the top emission type, the firstelectrode 300 may upwardly reflect the light emitted from the firstemission layer 500 and the second emission layer 700. In this case, thefirst electrode 300 may be formed in a double-layered structurecomprising a reflective layer for reflecting the light, and a conductivelayer configured to supply a hole to the first emission layer 500. Thereflective layer and the conductive layer may be in contact with eachother, or may be spaced apart from each other with an insulatingtherebetween.

The bank 400 is configured to at least partially cover both ends of thefirst electrode 300 on the circuit device layer 200. Accordingly, it ispossible to prevent a current from being concentrated into the ends ofthe first electrode 300, to thereby prevent a deterioration of emissionefficiency. The bank 400 is formed as a matrix configuration on theboundary area between each of the plurality of sub pixels (SP1, SP2,SP3), and is configured to define an emission area. That is, some areaof an upper surface of the first electrode 300, which is exposed withoutbeing covered by the bank 400, becomes the emission area.

The first emission layer 500 is provided in the sub pixel (SP1, SP2,SP3) area on the first electrode 300. Also, at least some layers of thefirst emission layer 500 may be provided on the boundary area betweeneach sub pixel (SP1, SP2, SP3). That is, at least some layers of thefirst emission layer 500 may be provided in the area overlapped with thebank 400.

The first emission layer 500 may include a first hole transport layer510, a first organic emission layer 520, and a first electron transportlayer 530. Although not shown, the first emission layer 500 may furtherinclude an additional hole injection layer provided below the first holetransport layer 510.

The first hole transport layer 510 may be provided in each sub pixel(SP1, SP2, SP3) area and the boundary area between each sub pixel (SP1,SP2, SP3). That is, the first hole transport layer 510 may be formed ina connected structure among the neighboring sub pixels (SP1, SP2, SP3),whereby the first hole transport layer 510 may be overlapped with thefirst electrode 300 and the bank 400 while being provided on the firstelectrode 300 and the bank 400.

The first organic emission layer 520 is provided on the first holetransport layer 510, and the first organic emission layer 520 may bepatterned in each sub pixel (SP1, SP2, SP3) area. That is, the firstorganic emission layer 520 may comprise an organic emission layerprovided in the first sub pixel (SP1) and configured to emit firstcolored light, for example, red (R) colored light, an organic emissionlayer provided in the second sub pixel (SP2) and configured to emitsecond colored light, for example, green (G) colored light, and anorganic emission layer provided in the third sub pixel (SP3) andconfigured to emit third colored light, for example, blue (B) coloredlight. The red organic emission layer, the green organic emission layer,and the blue organic emission layer are spaced apart from each otherwith the bank 400 therebetween.

The first electron transport layer 530 is provided on the first organicemission layer 520. Especially, the first electron transport layer 530may be provided in each sub pixel (SP1, SP2, SP3) area, and the boundaryarea between each sub pixel (SP1, SP2, SP3). Thus, the first electrontransport layer 530 may be overlapped with the bank 400. In the areaoverlapped with the bank 400, the first electron transport layer 530 maybe in contact with the first hole transport layer 510.

The charge generation layer 600 is provided between the first emissionlayer 500 and the second emission layer 700. The charge generation layer600 controls a charge balance between the first emission layer 500 andthe second emission layer 700. The charge generation layer 600 includesan N-type charge generation layer 610 and a P-type charge generationlayer 620.

The N-type charge generation layer 610 is provided on the first emissionlayer 500. Especially, the N-type charge generation layer 610 isprovided in each sub pixel (SP1, SP2, SP3) area. Meanwhile, someportions of the N-type charge generation layer 610 may be overlappedwith the bank 400.

The N-type charge generation layer 610 is provided to inject an electroninto the first emission layer 500. The N-type charge generation layermay be formed of an organic layer doped with alkali metal such as Li,Na, K or Cs, or alkali earth metal such as Mg, Sr, Ba or Ra.

The P-type charge generation layer 620 is provided on the N-type chargegeneration layer 610. Especially, the P-type charge generation layer 620is provided in each sub pixel (SP1, SP2, SP3) area. Meanwhile, someportions of the P-type charge generation layer 620 may be overlappedwith the bank 400.

The P-type charge generation layer 620 is provided to inject a hole intothe second emission layer 700. The P-type charge generation layer 620may be formed of an organic material with a hole transport capacitywhich is doped with P-type dopant.

In the boundary area between each sub pixel (SP1, SP2, SP3), a P-typedoping layer 615 is provided in the same layer as that of the N-typecharge generation layer 610, an N-type doping layer 625 is provided inthe same layer as that of the P-type charge generation layer 620. Thus,the P-type doping layer 615 and the N-type doping layer 625 are providedin the area overlapped with the bank 400, and the N-type doping layer625 may be in contact with an upper surface of the P-type doping layer615. That is, the N-type doping layer 625 may be overlapped with theP-type doping layer 615.

In detail, the P-type doping layer 615 is provided in each of the areabetween the N-type charge generation layer 610 of the first sub pixel(SP1) and the N-type charge generation layer 610 of the second sub pixel(SP2), the area between the N-type charge generation layer 610 of thesecond sub pixel (SP2) and the N-type charge generation layer 610 of thethird sub pixel (SP3), and the area between the N-type charge generationlayer 610 of the third sub pixel (SP3) and the N-type charge generationlayer 610 of the first sub pixel (SP1). Accordingly, the respectiveN-type charge generation layers 610 patterned in the respective subpixels (SP1, SP2, SP3) are spaced apart from each other with the P-typedoping layer 615 therebetween.

According as the N-type charge generation layer 610 is formed in aconnected structure among the sub pixels (SP1, SP2, SP3) while beingprovided on the entire boundary area between each sub pixel (SP1, SP2,SP3) as well as each sub pixel (SP1, SP2, SP3) area, charges generatedin any one sub pixel (SP1, SP2, SP3) may be transferred to theneighboring other sub pixel (SP1, SP2, SP3) through the N-type chargegeneration layer 610, whereby it may cause a leakage current in theother sub pixel (SP1, SP2, SP3). According to one embodiment of thepresent disclosure, the N-type charge generation layers 610 provided inthe respective sub pixels (SP1, SP2, SP3) are spaced apart from eachother with the P-type doping layer 615 therebetween, whereby the P-typedoping layer 615 may function as a barrier layer. Thus, it is possibleto prevent charges generated in any one N-type charge generation layer610 from being transferred to the neighboring other N-type chargegeneration layer 610, to thereby reduce a problem related with a leakagecurrent.

The N-type charge generation layer 610 and the P-type doping layer 615may be obtained by sequential steps of forming the N-type chargegeneration layer 610 on either at least a portion of the surface of thesubstrate 100 or an entire surface of the substrate 100, exposing someportions of the N-type charge generation layer 610 overlapped with thebank 400 while covering the other regions of the N-type chargegeneration layer 610 with a mask, and doping the exposed portions withP-type dopant. Accordingly, the N-type charge generation layer 610 andthe P-type doping layer 615 may be provided in the same layer, and maybe formed at the same or substantially the same thickness.

Also, the N-type doping layer 625 is provided in each of the areabetween the P-type charge generation layer 620 of the first sub pixel(SP1) and the P-type charge generation layer 620 of the second sub pixel(SP2), the area between the P-type charge generation layer 620 of thesecond sub pixel (SP2) and the P-type charge generation layer 620 of thethird sub pixel (SP3), and the area between the P-type charge generationlayer 620 of the third sub pixel (SP3) and the P-type charge generationlayer 620 of the first sub pixel (SP1). Accordingly, the P-type chargegeneration layers 620 patterned in the respective sub pixels (SP1, SP2,SP3) may be spaced apart from each other with the N-type doping layer625 therebetween. Thus, according to one embodiment of the presentdisclosure, the P-type charge generation layers 620 patterned in therespective sub pixels (SP1, SP2, SP3) are spaced apart from each otherwith the N-type doping layer 625 therebetween, whereby the N-type dopinglayer 625 functions as a barrier layer. Thus, it is possible to preventcharges generated in any one P-type charge generation layer 620 frombeing transferred to the neighboring other P-type charge generationlayer 620, to thereby reduce a problem related with a leakage current.

The P-type charge generation layer 620 and the N-type doping layer 625may be obtained by sequential steps of forming the P-type chargegeneration layer 620 on either at least a portion of the surface of thesubstrate 100 or an entire surface of the substrate 100, exposing someportions of the P-type charge generation layer 620 overlapped with thebank 400 while covering the other regions of the P-type chargegeneration layer 620 with a mask, and doping the exposed portions withN-type dopant. Accordingly, the P-type charge generation layer 620 andthe N-type doping layer 625 may be provided in the same layer, and maybe formed at the same or substantially the same thickness.

The second emission layer 700 is provided in the sub pixel (SP1, SP2,SP3) area on the charge generation layer 600. Also, at least some layersof the second emission layer 700 may be provided in the boundary areabetween each sub pixel (SP1, SP2, SP3) area on the N-type doping layer625. That is, at least some layers of the second emission layer 700 maybe provided in the area overlapped with the bank 400.

The second emission layer 700 includes a second hole transport layer710, a second organic emission layer 720, and a second electrontransport layer 730. Although not shown, the second emission layer 700may further include an additionally-provided electron injection layer onthe second electron transport layer 730.

The second hole transport layer 710 may be provided in both areas ofeach sub pixel (SP1, SP2, SP3) area and the boundary area between eachsub pixel (SP1, SP2, SP3) area. That is, the second hole transport layer710 may be formed in a connected structure between the neighboring subpixels (SP1, SP2, SP3), whereby the second hole transport layer 710 maybe provided on the P-type charge generation layer 620 and the N-typedoping layer 625. In other words, the second hole transport layer 710may be overlapped with the bank 400.

The second organic emission layer 720 is provided on the second holetransport layer 710. Especially, the second organic emission layer 720may be patterned in each sub pixel (SP1, SP2, SP3) area. That is, thesecond organic emission layer 720 may comprise an organic emission layerprovided in the first sub pixel (SP1) and configured to emit red (R)colored light, an organic emission layer provided in the second subpixel (SP2) and configured to emit green (G) colored light, and anorganic emission layer provided in the third sub pixel (SP3) andconfigured to emit blue (B) colored light. The red organic emissionlayer, the green organic emission layer, and the blue organic emissionlayer may be spaced apart from each other with the bank 400therebetween.

The second electron transport layer 730 is provided on the secondorganic emission layer 720. Especially, the second electron transportlayer 730 may be provided in both areas of each sub pixel (SP1, SP2,SP3) area and the boundary area between each sub pixel (SP1, SP2, SP3)area. Thus, the second electron transport layer 730 may be overlappedwith the bank 400. In the area overlapped with the bank 400, the secondelectron transport layer 730 may contact the second hole transport layer710.

The second electrode 800 is provided on the second emission layer 700.The second electrode 800 may function as a cathode of theelectroluminescent display device. The second electrode 800 may beprovided in each sub pixel (SP1, SP2, SP3) and also provided in theboundary area between each of the sub pixels (SP1, SP2, SP3).

The electroluminescent display device according to one embodiment of thepresent disclosure may be formed in a top emission type, whereby thesecond electrode 800 may include a transparent conductive materialcapable of upwardly transmitting light emitted from the first emissionlayer 500 and the second emission layer 700. Also, the second electrode800 may be formed of a semi-transparent electrode, whereby it ispossible to obtain a microcavity effect by each sub pixel (SP1, SP2,SP3). If the second electrode 800 is formed of the semi-transparentelectrode, it is possible to obtain a microcavity effect by a repetitivereflection and re-reflection between the second electrode 800 and thefirst electrode 300, to thereby improve light efficiency.

Although not shown, an encapsulation layer may be additionally providedon the second electrode 800 in order to prevent a permeation of externalmoisture or oxygen. The encapsulation layer may be formed of aninorganic insulating material, or may be provided in a structureobtained by alternately depositing an inorganic insulating material andan organic insulating material, but not limited to this structure.

FIGS. 2A to 2C illustrate a LUMO level and a HOMO level of the chargegeneration layer according to one embodiment of the present disclosure.FIG. 2A illustrates a charge mobility to {circle around (1)} arrowdirection in FIG. 1, FIG. 2B illustrates a charge mobility to {circlearound (2)} arrow direction in FIG. 1, and FIG. 2C illustrates a chargemobility to {circle around (3)} arrow direction in FIG. 1. In FIGS. 2Ato 2C, an energy level before an electric field (E-filed) is appliedthereto is shown in the left side, and an energy level after an electricfield (E-field) is applied thereto is shown in the right side. Also, anenergy level shown in a dotted line corresponds to a fermi level.

As shown in FIG. 2A, in each sub pixel (SP1, SP2, SP3) area, there is asmall difference of fermi level between the N-type charge generationlayer (N-CGL) and the P-type charge generation layer (P-CGL) before anelectric field (E-field) is applied thereto. Thus, if the fermi level isidentically maintained even after the application of an electric field(E-field), charges may be smoothly transferred owing to the smalldifference of energy level between the N-type charge generation layer(N-CGL) and the P-type charge generation layer (P-CGL). Accordingly, inFIG. 1, a charge transfer is smoothly carried out in the sub pixel (SP1,SP2, SP3) area, whereby it facilitates a light emission in the firstemission layer 500 and the second emission layer 700.

As shown in FIG. 2B, in the boundary area between each sub pixel (SP1,SP2, SP3) area, there is a large difference of fermi level between theP-type doping layer (P-dop) and the N-type doping layer (N-dop) beforean electric field (E-field) is applied thereto. Thus, if the fermi levelis identically maintained even after the application of an electricfield (E-field), charges are not smoothly transferred due to the largedifference of energy level between the P-type doping layer (P-dop) andthe N-type doping layer (N-dop). Accordingly, in FIG. 1, a chargetransfer is not carried out smoothly in the boundary area between eachsub pixel (SP1, SP2, SP3) area, whereby it is not easy to make a lightemission in the first emission layer 500 and the second emission layer700.

As shown in FIG. 2C, in the boundary area between each sub pixel (SP1,SP2, SP3) area, there is a large difference of fermi level between theN-type charge generation layer (N-CGL) and the P-type doping layer(P-dop) before an electric field (E-field) is applied thereto. Thus, ifthe fermi level is identically maintained even after the application ofan electric field (E-field), charges are not smoothly transferred due tothe large difference of energy level between the N-type chargegeneration layer (N-CGL) and the P-type doping layer (P-dop).Accordingly, in FIG. 1, charges are not transferred smoothly to left andright directions in the boundary area between each sub pixel (SP1, SP2,SP3) area, whereby it is possible to prevent a leakage current.

FIG. 3 is a graph of a current density change in accordance with adriving voltage according to one embodiment of the present disclosure.FIG. 3 is a graph of a current density change according to a drivingvoltage in the {circle around (1)} arrow direction, the {circle around(2)} arrow direction, and the {circle around (3)} arrow direction ofFIG. 1.

As shown in FIG. 3, in the voltage less than 2 volts, a current densitychange is similar in the {circle around (1)} arrow direction, the{circle around (2)} arrow direction, and the {circle around (3)} arrowdirection. However, in the voltage of 2 volts or more than 2 volts, ahigh current density is shown only in the {circle around (1)} arrowdirection, and a low current density is shown in the {circle around (2)}arrow direction and the {circle around (3)} arrow direction.

Accordingly, in the voltage of 2 volts or more than 2 volts, a lightemission of the first emission layer 500 and the second emission layer700 is easily carried out in the sub pixel (SP1, SP2, SP3) area, and alight emission of the first emission layer 500 and the second emissionlayer 700 is not easily carried out in the boundary area between eachsub pixel (SP1, SP2, SP3) area, whereby charges are not transferredsmoothly to left and right directions in the boundary area between eachsub pixel (SP1, SP2, SP3) area, whereby it is possible to prevent aleakage current.

FIG. 4 is a schematic cross sectional view illustrating anelectroluminescent display device according to another embodiment of thepresent disclosure. Except a structure change in a first hole transportlayer 510 and a second hole transport layer 710, the electroluminescentdisplay device of FIG. 4 is identical in structure to the aforementionedelectroluminescent display device of FIG. 1. Accordingly, the sameelements are denoted by the same reference numerals, and only thedifferent structures will be described in detail as follows.

As shown in FIG. 4, a first hole transport layer 510 is provided in eachsub pixel (SP1, SP2, SP3) area. In the boundary area between each subpixel (SP1, SP2, SP3), an N-type doping layer 515 is provided in thesame layer as that of the first hole transport layer 510. That is, theN-type doping layer 515 is provided in the area overlapped with a bank400. Also, the N-type doping layer 515 may be overlapped with theaforementioned N-type doping layer 625 and P-type doping layer 615.Also, a portion of the first hole transport layer 510 may be overlappedwith the bank 400.

In detail, the N-type doping layer 515 is provided in each of the areabetween the first hole transport layer 510 of the first sub pixel (SP1)and the first hole transport layer 510 of the second sub pixel (SP2),the area between the first hole transport layer 510 of the second subpixel (SP2) and the first hole transport layer 510 of the third subpixel (SP3), and the area between the first hole transport layer 510 ofthe third sub pixel (SP3) and the first hole transport layer 510 of thefirst sub pixel (SP1). Accordingly, the first hole transport layers 510patterned in the respective sub pixels (SP1, SP2, SP3) may be spacedapart from each other with the N-type doping layer 515 therebetween.

In this case, the first hole transport layer 510 may be formed of anorganic layer with conductivity, which is doped with P-type dopant. Ifthe first hole transport layer 510 is provided in the entire areacomprising the boundary area between each sub pixel (SP1, SP2, SP3) aswell as each sub pixel (SP1, SP2, SP3), and is formed in a connectedstructure among the sub pixels (SP1, SP2, SP3), charges generated in anyone sub pixel (SP1, SP2, SP3) may be transferred to another neighboringsub pixel (SP1, SP2, SP3) through the first hole transport layer 510,whereby it may have a problem related with a leakage current in anotherneighboring sub pixel (SP1, SP2, SP3). According to another embodimentof the present disclosure, the first hole transport layers 510 patternedin the respective sub pixels (SP1, SP2, SP3) may be spaced apart fromeach other with the N-type doping layer 515 therebetween, whereby theN-type doping layer 515 functions as a barrier layer. Thus, it ispossible to prevent charges generated in any one sub pixel (SP1, SP2,SP3) from being transferred to another neighboring sub pixel (SP1, SP2,SP3), to thereby reduce a leakage current problem.

The first hole transport layer 510 and the N-type doping layer 515 maybe obtained by sequential steps of forming the first hole transportlayer 510 on either at least a portion of the surface of the substrate100 or an entire surface of the substrate 100, exposing some portions ofthe first hole transport layer 510 overlapped with the bank 400 whilecovering the other regions of the first hole transport layer 510 with amask, and doping the exposed portions with N-type dopant. Accordingly,the first hole transport layer 510 and the N-type doping layer 515 maybe provided in the same layer, and may be formed at the same orsubstantially the same thickness.

Also, a second hole transport layer 710 is provided in each sub pixel(SP1, SP2, SP3) area. In the boundary area between each sub pixel (SP1,SP2, SP3), an N-type doping layer 715 is provided in the same layer asthat of the second hole transport layer 710. That is, the N-type dopinglayer 715 is provided in the area overlapped with the bank 400. Also, aportion of the second hole transport layer 710 may be overlapped withthe bank 400.

In detail, the N-type doping layer 715 is provided in each of the areabetween the second hole transport layer 710 of the first sub pixel (SP1)and the second hole transport layer 710 of the second sub pixel (SP2),the area between the second hole transport layer 710 of the second subpixel (SP2) and the second hole transport layer 710 of the third subpixel (SP3), and the area between the second hole transport layer 710 ofthe third sub pixel (SP3) and the second hole transport layer 710 of thefirst sub pixel (SP1). Accordingly, the second hole transport layers 710patterned in the respective sub pixels (SP1, SP2, SP3) may be spacedapart from each other with the N-type doping layer 715 therebetween.

In this case, the second hole transport layer 710 may be formed of anorganic layer with conductivity, which is doped with P-type dopant.According to another embodiment of the present disclosure, the secondhole transport layers 710 patterned in the respective sub pixels (SP1,SP2, SP3) may be spaced apart from each other with the N-type dopinglayer 715 therebetween, whereby the N-type doping layer 715 functions asa barrier layer. Thus, it is possible to prevent charges generated inthe second hole transport layer 710 of any one sub pixel from beingtransferred to the second hole transport layer 710 of a neighboringanother sub pixel, to thereby reduce a leakage current problem.

The second hole transport layer 710 and the N-type doping layer 715 maybe obtained by sequential steps of forming the second hole transportlayer 710 on either at least a portion of the surface of the substrate100 or an entire surface of the substrate 100, exposing some portions ofthe second hole transport layer 710 overlapped with the bank 400 whilecovering the other regions of the second hole transport layer 710 with amask, and doping the exposed portions with N-type dopant. Accordingly,the second hole transport layer 710 and the N-type doping layer 715 maybe provided in the same layer, and may be formed at the same orsubstantially the same thickness.

Meanwhile, any one of the first hole transport layer 510 and the secondhole transport layer 710 may be formed in a consecutively connectedstructure in the respective sub pixels (SP1, SP2, SP3) and the boundaryarea between each sub pixel (SP1, SP2, SP3) as shown in FIG. 1.

FIG. 5 is a schematic cross sectional view illustrating anelectroluminescent display device according to another embodiment of thepresent disclosure. The electroluminescent display device of FIG. 5 isdifferent in structure of a first organic emission layer 520 and asecond organic emission layer 720 from the electroluminescent displaydevice of FIG. 1. Accordingly, the same elements are denoted by the samereference numerals, and only the different structures will be describedin detail as follows.

As shown in FIG. 5, a first organic emission layer 520 is providedbetween a first hole transport layer 510 and a first electron transportlayer 530, and the first organic emission layer 520 is identical instructure to the first hole transport layer 510 and the first electrontransport layer 530. That is, the first organic emission layer 520 isprovided both in each sub pixel (SP1, SP2, SP3) area and the boundaryarea between each sub pixel (SP1, SP2, SP3) area.

Also, a second organic emission layer 720 is provided between a secondhole transport layer 710 and a second electron transport layer 730, andthe second organic emission layer 720 is identical in structure to thesecond hole transport layer 710 and the second electron transport layer730. That is, the second organic emission layer 720 is provided both ineach sub pixel (SP1, SP2, SP3) area and the boundary area between eachsub pixel (SP1, SP2, SP3) area.

In this case, the first organic emission layer 520 is configured to emitblue (B) colored light, and the second organic emission layer 720 isconfigured to emit yellowish green (YG) colored light. Accordingly, theblue (B) colored light emitted from the first organic emission layer5210 is mixed with the yellowish green (YG) colored light emitted fromthe second organic emission layer 720, to thereby make white coloredlight. According as the white colored light is emitted, a color filter900 may be additionally provided in each sub pixel (SP1, SP2, SP3). Forexample, a red (R) color filter 900 is provided in the first sub pixel(SP1), a green (G) color filter 900 is provided in the second sub pixel(SP2), and a blue (B) color filter 900 is provided in the third subpixel (SP3). The color filter 900 may be provided on a second electrode800. Although not shown, an encapsulation layer may be additionallyprovided on the second electrode 800. In this case, the color filter 900may be provided on the encapsulation layer.

Meanwhile, the first organic emission layer 520 is provided to emityellowish green (YG) colored light, and the second organic emissionlayer 720 may be provided to emit blue (B) colored light.

FIG. 6 is a schematic cross sectional view illustrating anelectroluminescent display device according to another embodiment of thepresent disclosure. The electroluminescent display device of FIG. 6 isdifferent in structure of a first organic emission layer 520 and asecond organic emission layer 720 from the electroluminescent displaydevice of FIG. 4. Accordingly, the same elements are denoted by the samereference numerals, and only the different structures will be describedin detail as follows.

As shown in FIG. 6, a first organic emission layer 520 is provided bothin each sub pixel (SP1, SP2, SP3) area and the boundary area betweeneach sub pixel (SP1, SP2, SP3) area.

Also, a second organic emission layer 720 is provided both in each subpixel (SP1, SP2, SP3) area and the boundary area between each sub pixel(SP1, SP2, SP3) area.

In this case, the first organic emission layer 520 is configured to emitblue (B) colored light, and the second organic emission layer 720 may beconfigured to emit yellowish green (YG) colored light. Accordingly, theblue (B) colored light emitted from the first emission layer 500 ismixed with the yellowish green (YG) colored light emitted from thesecond emission layer 700, to thereby emit white colored light.According as the white colored light is emitted, a color filter 900 maybe additionally provided in each sub pixel (SP1, SP2, SP3). For example,a red (R) color filter 900 is provided in the first sub pixel (SP1), agreen (G) color filter 900 is provided in the second sub pixel (SP2),and a blue (B) color filter 900 is provided in the third sub pixel(SP3). The color filter 900 may be provided on a second electrode 800.Although not shown, an encapsulation layer may be additionally providedon the second electrode 800. In this case, the color filter 900 may beprovided on the encapsulation layer.

Meanwhile, the first organic emission layer 520 may be provided to emityellowish green (YG) colored light, and the second organic emissionlayer 720 may be provided to emit blue (B) colored light.

Although not shown, another embodiment of the present disclosure mayinclude a first emission layer configured to emit red colored light, asecond emission layer configured to emit green colored light, a thirdemission layer configured to emit blue colored light, a first chargegeneration layer provided between the first emission layer and thesecond emission layer, and a second charge generation layer providedbetween the second emission layer and the third emission layer. At thistime, in the same manner as the charge generation layer 600 of theaforementioned embodiment, each of the first charge generation layer andthe second charge generation layer may include respective N-type chargegeneration layers 610 which are spaced apart from each other with aP-type doping layer 615 therebetween, and respective P-type chargegeneration layers 620 which are spaced apart from each other with anN-type doping layer 625 therebetween. Also, in the same manner as theaforementioned embodiment, at least one of the first to third emissionlayers may include hole transport layers 510 and 710 which are spacedapart from each other with an N-type doping layer 515 and 715therebetween.

Also, in another embodiment of the present disclosure, one emissionlayer without a charge generation layer may be provided between a firstelectrode 300 and a second electrode 800, and the emission layer mayinclude hole transport layers 510 and 710 which are spaced apart fromeach other with an N-type doping layer 515 and 715 therebetween, in thesame manner as the aforementioned embodiment.

FIG. 7 is a schematic plan view illustrating the electroluminescentdisplay device according to one embodiment of the present disclosure.

As shown in FIG. 7, the electroluminescent display device according toone may include a first pixel (P1) and a second pixel (P2) which areclose to each other in up and down directions. Each of the first pixel(P1) and the second pixel (P2) includes a first sub pixel (SP1), asecond sub pixel (SP2), and a third sub pixel (SP3). The first sub pixel(SP1) of the first pixel (P1) and the first sub pixel (SP1) of thesecond sub pixel (SP2) are arranged in the same column, the second subpixel (SP2) of the first pixel (P1) and the second sub pixel (SP2) ofthe second pixel (P2) are arranged in the same column, and the third subpixel (SP3) of the first pixel (P1) and the third sub pixel (SP3) of thesecond pixel (P2) are arranged in the same column.

In this case, the N-type doping layer 515, 625 and 715 and the P-typedoping layer 615, which are described in the aforementioned variousembodiments of the present disclosure, are provided in the boundary areabetween the first sub pixel (SP1) and the second sub pixel (SP2) and theboundary area between the second sub pixel (SP2) and the third sub pixel(SP3). That is, the N-type doping layer 515 provided between the firsthole transport layers 510, the N-type doping layer 625 provided betweenthe P-type charge generation layers 620, the N-type doping layer 715provided between the second hole transport layers 710, and the P-typedoping layer 615 provided between the N-type charge generation layers610 are provided in the boundary area between each of the sub pixels(SP1, SP2, SP3).

In this case, the N-type doping layer 515, 625 and 715 and the P-typedoping layer 615 may be consecutively provided between the first pixel(P1) and the second pixel (P2), whereby it is possible to form an entirestripe structure.

FIG. 8 is a schematic plan view illustrating the electroluminescentdisplay device according to another embodiment of the presentdisclosure. According as the N-type doping layer 515, 625 and 715 andthe P-type doping layer 615 are additionally provided in the boundaryarea between the first pixel (P1) and the second pixel (P2), theelectroluminescent display device of FIG. 8 is different from theelectroluminescent display device of FIG. 7. Hereinafter, only thedifferent structures will be described in detail.

The first sub pixel (SP1) of the first pixel (P1) and the first subpixel (SP1) of the second pixel (P2), which are arranged in the samecolumn, may be configured to emit the same first color light, forexample, red (R) colored light. In this case, even though a leakagecurrent is generated between the first sub pixel (SP1) of the firstpixel (P1) and the first sub pixel (SP1) of the second pixel (P2), adeterioration of picture quality is not significant.

Also, the second sub pixel (SP2) of the first pixel (P1) and the secondsub pixel (SP2) of the second pixel (P2), which are arranged in the samecolumn, may be configured to emit the same second color light, forexample, green (G) colored light. In this case, even though a leakagecurrent is generated between the second sub pixel (SP2) of the firstpixel (P1) and the second sub pixel (SP2) of the second pixel (P2), adeterioration of picture quality is not significant.

Also, the third sub pixel (SP3) of the first pixel (P1) and the thirdsub pixel (SP3) of the second pixel (P2), which are arranged in the samecolumn, may be configured to emit the same third color light, forexample, blue (B) colored light. In this case, even though a leakagecurrent is generated between the third sub pixel (SP3) of the firstpixel (P1) and the third sub pixel (SP3) of the second pixel (P2), adeterioration of picture quality is not significant.

Accordingly, in case of FIG. 7, the N-type doping layer 515, 625 and 715and the P-type doping layer 615, which function as a barrier layer, arenot provided in the boundary area between the first sub pixel (SP1) ofthe first pixel (P1) and the first sub pixel (SP1) of the second pixel(P2), the boundary area between the second sub pixel (SP2) of the firstpixel (P1) and the second sub pixel (SP2) of the second pixel (P2), andthe boundary area between the third sub pixel (SP3) of the first pixel(P1) and the third sub pixel (SP3) of the second pixel (P2).

Meanwhile, in case of FIG. 8, the N-type doping layer 515, 625 and 715and the P-type doping layer 615 are provided in the boundary areabetween the first sub pixel (SP1) of the first pixel (P1) and the firstsub pixel (SP1) of the second pixel (P2), the boundary area between thesecond sub pixel (SP2) of the first pixel (P1) and the second sub pixel(SP2) of the second pixel (P2), and the boundary area between the thirdsub pixel (SP3) of the first pixel (P1) and the third sub pixel (SP3) ofthe second pixel (P2), to thereby prevent a leakage current between thefirst pixel (P1) and the second pixel (P2).

Accordingly, in case of FIG. 8, the N-type doping layer 515, 625 and 715and the P-type doping layer 615 may be provided in a matrixconfiguration which is identical to that of the aforementioned bank 400.

FIGS. 9A to 9C relate to an electroluminescent display device accordingto another embodiment of the present disclosure and relate to ahead-mounted display (HMD) apparatus. FIG. 9A is a schematic perspectiveview, FIG. 9B is a schematic plan view of a virtual reality (VR)structure, and FIG. 9C is a schematic cross-sectional view of anaugmented reality (AR) structure.

As seen in FIG. 9A, the HMD apparatus according to the presentdisclosure may include an accommodating case 10 and a head-mounted band30.

The accommodating case 10 may accommodate elements such as a displayapparatus, a lens array, and an eyepiece lens.

The head-mounted band 30 may be fixed to the accommodating case 10. Thehead-mounted band 30 is illustrated as being provided to surround anupper surface and both side surfaces of a user, but is not limitedthereto. The head-mounted band 30 may fix the HMD apparatus to a head ofa user and may be replaced by a glasses frame type structure or a helmettype structure.

As seen in FIG. 9B, an HMD apparatus having the VR structure accordingto the present disclosure may include a left-eye display apparatus 12, aright-eye display apparatus 11, a lens array 13, a left-eye eyepiecelens 20 a, and a right-eye eyepiece lens 20 b.

The left-eye display apparatus 12, the right-eye display apparatus 11,the lens array 13, the left-eye eyepiece lens 20 a, and the right-eyeeyepiece lens 20 b may be accommodated into the accommodating case 10.

The left-eye display apparatus 12 and the right-eye display apparatus 11may display the same image, and in this case, a user may watch atwo-dimensional (2D) image. Alternatively, the left-eye displayapparatus 12 may display a left-eye image, and the right-eye displayapparatus 11 may display a right-eye image. Each of the left-eye displayapparatus 12 and the right-eye display apparatus 11 may be configured asthe electroluminescent display device as explained above. In this case,an upper portion corresponding to a surface displaying an image may facethe lens array 13.

The lens array 13 may be spaced apart from each of the left-eye eyepiecelens 20 a and the left-eye display apparatus 12 and may be providedbetween the left-eye eyepiece lens 20 a and the left-eye displayapparatus 12. That is, the lens array 13 may be disposed in front of theleft-eye eyepiece lens 20 a and behind the left-eye display apparatus12. Also, the lens array 13 may be spaced apart from each of theright-eye eyepiece lens 20 b and the right-eye display apparatus 11 andmay be provided between the right-eye eyepiece lens 20 b and theright-eye display apparatus 11. That is, the lens array 13 may bedisposed in front of the right-eye eyepiece lens 20 b and behind theright-eye display apparatus 11.

The lens array 13 may be a micro-lens array. The lens array 13 may bereplaced by a pin hole array. By using the lens array 13, an imagedisplayed by the left-eye display apparatus 12 or the right-eye displayapparatus 11 may be zoomed in by a certain magnification, and thus, azoomed-in image may be seen by a user.

A left eye LE of a user may be located at the left-eye eyepiece lens 20a, and a right eye RE of the user may be located at the right-eyeeyepiece lens 20 b.

As seen in FIG. 9C, an HMD apparatus having the AR structure accordingto the present disclosure may include a left-eye display apparatus 12, alens array 13, a left-eye eyepiece lens 20 a, a transmissive reflectionpart 14, and a transmissive window 15. In FIG. 9C, for convenience, onlyleft-eye elements are illustrated, and right-eye elements may be thesame as the left-eye elements.

The left-eye display apparatus 12, the lens array 13, the left-eyeeyepiece lens 20 a, the transmissive reflection part 14, and thetransmissive window 15 may be accommodated into the accommodating case10.

The left-eye display apparatus 12 may be disposed in one side (forexample, an upper side) of the transmissive reflection part 14 withoutcovering the transmissive window 15. Therefore, the left-eye displayapparatus 12 may provide an image to the transmissive reflection part 14without covering an external background seen through the transmissivewindow 15.

The left-eye display apparatus 12 may be configured as theelectroluminescent display device as explained above. In this case, anupper portion corresponding to a surface displaying an image may facethe transmissive reflection part 14.

The lens array 13 may be provided between the left-eye eyepiece lens 20a and the transmissive reflection part 14.

The left eye of the user may be located at the left-eye eyepiece lens 20a.

The transmissive reflection part 14 may be disposed between the lensarray 13 and the transmissive window 15. The transmissive reflectionpart 14 may include a reflection surface 14 a which transmits a portionof light and reflects the other portion of the light. The reflectionsurface 14 a may be provided so that an image displayed by the left-eyedisplay apparatus 12 travels to the lens array 13. Accordingly, the usermay see, through the transmissive window 15, all of the externalbackground and the image displayed by the left-eye display apparatus 12.That is, the user may see one image which includes a real background anda virtual image, and thus, AR may be implemented.

The transmissive window 15 may be disposed in front of the transmissivereflection part 14.

According to one embodiment of the present disclosure, the organic layerprovided in the first sub pixel and the organic layer provided in thesecond sub pixel are spaced apart from each other with the doping layerprovided in the boundary area between the first sub pixel and the secondsub pixel, and the doping layer is doped with dopant whose polarity isopposite to that of the organic layer, whereby the doping layerfunctions as a barrier layer. Accordingly, it is possible to prevent aleakage current between the first sub pixel and the second sub pixelwhich are adjacent to each other through the organic layer, to therebyprevent a deterioration of picture quality caused by the leakagecurrent.

It will be apparent to those skilled in the art that the presentdisclosure described above is not limited by the above-describedembodiments and the accompanying drawings and that varioussubstitutions, modifications, and variations can be made in the presentdisclosure without departing from the spirit or scope of thedisclosures. Consequently, the scope of the present disclosure isintended to include all variations or modifications, and equivalentconcept that falls within the teachings of the present disclosure.

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. An electroluminescent display device, comprising: a substrate; afirst sub pixel and a second sub pixel on the substrate; a P-type dopinglayer between the first sub pixel and the second sub pixel; a firstelectrode in each of the first sub pixel and the second sub pixel on thesubstrate; a first emission layer on the first electrode; a chargegeneration layer on the first emission layer, including: an N-typecharge generation layer on the first emission layer; and a P-type chargegeneration layer on the N-type charge generation layer; a secondemission layer on the charge generation layer; and a second electrode onthe second emission layer, wherein the N-type charge generation layerprovided in the first sub pixel and the N-type charge generation layerprovided in the second sub pixel are spaced apart from each other withthe P-type doping layer provided in a boundary area between the firstsub pixel and the second sub pixel.
 2. The electroluminescent displaydevice according to claim 1, wherein the P-type doping layer is providedin the same layer as that of the N-type charge generation layer, and theP-type doping layer has the same or substantially the same thickness asthat of the N-type charge generation layer.
 3. The electroluminescentdisplay device according to claim 1, further comprising a bank betweenthe first sub pixel and the second sub pixel, wherein the P-type dopinglayer is overlapped with the bank provided in the boundary area betweenthe first sub pixel and the second sub pixel.
 4. The electroluminescentdisplay device according to claim 1, wherein the P-type doping layerincludes a material for the N-type charge generation layer doped with aP-type dopant.
 5. The electroluminescent display device according toclaim 1, further comprising an N-type doping layer between the first subpixel and the second sub pixel, wherein the P-type charge generationlayer provided in the first sub pixel and the P-type charge generationlayer provided in the second sub pixel are spaced apart from each otherwith the N-type doping layer provided in the boundary area between thefirst sub pixel and the second sub pixel.
 6. The electroluminescentdisplay device according to claim 5, wherein the N-type doping layer isprovided in the same layer as that of the P-type charge generationlayer, and the N-type doping layer has the same or substantially thesame thickness as that of the P-type charge generation layer.
 7. Theelectroluminescent display device according to claim 5, wherein theN-type doping layer is overlapped with the P-type doping layer.
 8. Theelectroluminescent display device according to claim 5, wherein theN-type doping layer is obtained by doping a material for the P-typecharge generation layer with N-type dopant.
 9. The electroluminescentdisplay device according to claim 1, further comprising an N-type dopinglayer between the first sub pixel and the second sub pixel, wherein atleast one of the first emission layer and the second emission layerincludes a hole transport layer, and wherein the hole transport layerprovided in the first sub pixel and the hole transport layer provided inthe second sub pixel are spaced apart from each other with the N-typedoping layer provided in the boundary area between the first sub pixeland the second sub pixel.
 10. The electroluminescent display deviceaccording to claim 9, wherein the N-type doping layer is provided in thesame layer as that of the hole transport layer, and the N-type dopinglayer has the same or substantially the same thickness as that of thehole transport layer.
 11. An electroluminescent display device,comprising: a substrate having thereon a first sub pixel and a secondsub pixel; a first N-type doping layer between the first sub pixel andthe second sub pixel; a first electrode in each of the first sub pixeland the second sub pixel on the substrate; an emission layer on thefirst electrode; and a hole transport layer included in the emissionlayer; and a second electrode on the emission layer, wherein the holetransport layer provided in the first sub pixel and the hole transportlayer provided in the second sub pixel are spaced apart from each otherwith the first N-type doping layer provided in the boundary area betweenthe first sub pixel and the second sub pixel.
 12. The electroluminescentdisplay device according to claim 11, wherein the first N-type dopinglayer is provided in the same layer as that of the hole transport layer,and the first N-type doping layer has the same or substantially the samethickness as that of the hole transport layer.
 13. Theelectroluminescent display device according to claim 11, furthercomprising a bank between the first sub pixel and the second sub pixel,wherein the first N-type doping layer is overlapped with the bankprovided in the boundary area between the first sub pixel and the secondsub pixel.
 14. The electroluminescent display device according to claim11, wherein the first N-type doping layer is obtained by doping amaterial for the hole transport layer with N-type dopant.
 15. Theelectroluminescent display device according to claim 11, furthercomprising: a charge generation layer including an N-type chargegeneration layer and a P-type charge generation layer; a P-type dopinglayer between the first sub pixel and the second sub pixel; and a secondN-type doping layer between the first sub pixel and the second subpixel, wherein the emission layer includes a first emission layer and asecond emission layer spaced apart from each other with the chargegeneration layer therebetween, wherein the N-type charge generationlayer is on the first emission layer, and the P-type charge generationlayer is on the N-type charge generation layer, and wherein the N-typecharge generation layer provided in the first sub pixel and the N-typecharge generation layer provided in the second sub pixel are spacedapart from each other with a P-type doping layer provided in theboundary area between the first sub pixel and the second sub pixel, andthe P-type charge generation layer provided in the first sub pixel andthe P-type charge generation layer provided in the second sub pixel arespaced apart from each other with the second N-type doping layerprovided in the boundary area between the first sub pixel and the secondsub pixel.
 16. The electroluminescent display device according to claim15, wherein the first N-type doping layer, the P-type doping layer, andthe second N-type doping layer are overlapped with each other.
 17. Adisplay device, comprising: a substrate; a first sub pixel and a secondsub pixel on the substrate; a doping layer between the first sub pixeland the second sub pixel; a first electrode in each of the first subpixel and the second sub pixel on the substrate; an organic layer witheither P-type polarity or N-type polarity on the first electrode; and asecond electrode on the organic layer, wherein the organic layerprovided in the first sub pixel and the organic layer provided in thesecond sub pixel are spaced apart from each other with the doping layerprovided in the boundary area between the first sub pixel and the secondsub pixel, and the doping layer is doped with dopant whose polarity isopposite to that of the organic layer.
 18. The display device accordingto claim 17, further comprising: a first emission layer between thefirst electrode and the second electrode; a first hole transport layerincluded in the first emission layer; an N-type charge generation layerincluded in the first emission layer; a P-type charge generation layerincluded in the first emission layer; a second emission layer betweenthe first electrode and the second electrode; and a second holetransport layer included in the second emission layer, and wherein theorganic layer includes at least one among the first hole transportlayer, the N-type charge generation layer, the P-type charge generationlayer, and the second hole transport layer.
 19. The display deviceaccording to claim 17, wherein the doping layer is patterned in a stripeconfiguration or a matrix configuration.
 20. The display deviceaccording to claim 17, further comprising: a lens array spaced apartfrom the substrate; and a receiving case for accommodating the substrateand the lens array.